A carbon nanotube (CNT) is a tubular material formed by rolling up a graphite piece. The structure can be divided into two forms, the single-walled type and the multi-walled type. Since the carbon nanotube has been discovered, it is found having the properties of high aspect ratio, small curvature radius at the sharp structure, high tensile strength, great heat conductivity, good super-conductivity at room temperature, and high chemical stability. Furthermore, the conductivity of CNT can easily be changed when CNT is made into nano-line or nano-semiconductor by various rolling-up means. Therefore, CNT has become the most popular research object for the scientists recently.
Nowadays, the methods for manufacturing carbon nanotubes include the arc-discharge method, the laser ablation method, the chemical vapor deposition method, and the organic metal pyrolysis method. The carbon nanotubes made by the respective method described above are all different. For example, the carbon nanotube can either be formed with a diameter ranged from one to hundreds of nanometers or be formed with a length ranged from hundreds of nanometers to hundreds of millimeters. Due to the carbon nanotube has the properties of compact volume, high strength, great heat conductivity and high electricity conductivity, and low power-consuming, it has been thought as the superior materials for developing various application products at the nanometer-level. For instance, the carbon nanotube can be used for manufacturing a transistor. In which, the carbon nanotube can be used as the electric current channel and the intensity of the electricity fields effecting on the carbon nanotube are changed by inputting various gate voltages. Accordingly, the transistor can be turned on or turned off simply by controlling the width of the current channel. Furthermore, the carbon nanotubes can also be applied to the manufacture of the field emission display and the probe for the atomic force microscopy. The resolution of the atomic force microscopy will be substantially improved by the probe made of the carbon nanotubes.
In the conventional method of manufacturing a carbon nanotube, it does not matter whether the finished products of carbon nanotubes are two-dimension or three-dimension structures, each carbon nanotube is usually a web structure with similar diameter. During the manufacturing process, a few components are including are necessarily provided in advance, including at least a substrate, a metal powder, and a reagent gas containing a carbon. Next, the reaction is performed under high temperature, and then the carbon nanotubes are grown and formed from the plural concaves on the substrate mentioned early. In the conventional method, the carbon nanotubes are usually grown without controlling their directions and densities. However, the directions and densities of the formed carbon nanotubes will affect the efficiency and the prime cost of the relative products. The product made of carbon nanotubes having one single direction will have a more complete structure, a better heat conductivity and a better electricity conductivity. Contrarily, the product made of carbon nanotubes without one single direction will not reveal the properties of great heat conductivity and high electricity conductivity as they are supposed to reveal. Furthermore, if the density of the carbon nanotubes is not high enough, the corresponding product will not fully reveal the excellent properties of the carbon nanotubes, such as great heat conductivity and high electricity conductivity, and high tensile intensity. Oppositely, if the density of the carbon nanotubes is too high, the corresponding high production costs will be wasted meaninglessly.
As above-mentioned, a method for controlling the manufactured carbon nanotubes on selective areas with a desired growing direction and a desired density will have great utility in the relevant industries.
Because of the technical defects described above, the applicant keeps on carving unflaggingly to develop a “SELECTIVE AREA GROWTH OF CARBON NANOTUBES BY METAL IMPRINT METHOD” through wholehearted experience and research.